Showing papers by "Federal University of São Carlos published in 1983"

Cytogenetic Considerations on the Genus Astyanax (Pisces, Characidae). I. Karyotypic Variability

Abstract: SUMMARYA study was carried out on mitotic and meiotic chromosomes of four species of the genus Astyanax (Pisces, Characidae) from three different water basins in the State of Sao Paulo, Brazil. The following karyotypic characteristics were observed: A. bimaculatus, 2n = 50 (n = 25, FN = 86–88); A. fasciatus, 2n = 46 (n = 23, FN = 90); « A. fasciatus » from the Juquia river, 2n = 48 (n = 24, FN = 94); A. schubarti, 2n = 36 (n = 18, FN = 70) and A. scabripinnis paranae, 2n = 50 (n = 25, FN = 90–92). The diversity in the number and morphology of the chromosomes suggests a model of non-conservative karyotypic evolution in this genus, with chromosome rearrangements of the centric fusion/fission type and/or inversion playing an important role in these alterations. On the basis of its characteristics, A. schubarti has the most differentiated karyotype and, in view of the low diploid number and small number of subtelocentric-acrocentric chromosomes, is probably of most recent origin. The two karyotypes encountere...

Evidence for a System of Supernumerary Chromosomes in Prochilodus Scrofa Steindachner, 1881 (Pisces, Prochilodontidae)

Abstract: SUMMARYBoth males and females of the fish Prochilodus scrofa have a diploid number of 2n = 54. However, with the exception of a single female, all 59 specimens (25 ♀, 34 ♂) studied had 1–5 minutes accessory chromosomes. The unstable behavior of these chromosomes during mitosis and meiosis as well as their heterochromatic nature, as detected by C-banding, are characteristics that emphasize their supernumerary nature. This is the first report of chromosomes of this type in the Osteichthyes (Pisces).

Multiple sex chromosomes in the genus Hoplias (Pisces, Erythrinidae)

Abstract: Cytogenetic studies were made in two populations of Hoplias sp. (Pisces, Erythrinidae) from the Lobo Reservoir, State of Sao Paulo, Brazil, and from the Aripuana River, State of Mato Grosso, Brazil. The two populations show evidences of multiple sex chromosomes. The animals from the Lobo Reservoir has an X1X1X2X2/X1X2Y mechanism, and those from the Aripuana River an XX/XY1Y2 mechanism, this representing the first such case described for fishes.

Cytogenetic Considerations on the Genus Astyanax (Pisces, Characidae). II. Occurrence of Natural Triploidy

Abstract: SUMMARYAstyanax schubarti is characterized by a diploid number of 36 chromosomes. In the present paper we report on the occurrence of a specimen with 54 chromosomes, a probable case of natural triploidy as shown not only by the chromosome number but also by the good morphological correspondence between the chromosomes of the 3x and 2x individuals. The fertilization of an unreduced oocyte is postulated as the probable cause of this triploidy.

Adaptative features of ectothermic enzymes--IV. Studies on malate dehydrogenase of Astyanax fasciatus (Characidae) from Lobo Reservoir (Såo Carlos, Såo Paulo, Brasil).

Abstract: 1. Skeletal muscle and heart supernatant malate dehydrogenase (s-MDH) from a subtropical fish, Astyanax fasciatus consists of three electrophoretically anodal bands. Each band is a dimer (AA, AB and BB) and two loci are active. 2. In A. fasciatus tissue extracts, A and B subunits are present at differing quantitative levels and their activities are almost season-independent. However, the relative activity of each homodimer in relation to total s-MDH estimated by densitometry of gels or of each homodimer purified by chromatography varies with temperature. The more anodic homodimer is thermolabile and the less anodic one is thermostable. 3. The pH optimum of s-MDH is 7.5, of AA is 6.5 and of BB is 7.8. 4. The BB isozyme is more sensitive to high concentrations of substrate and has a Km temperature-independent. The AA isozyme is not inhibited by high concentrations of oxaloacetate and shows a Km temperature-dependent with a fourteenfold increase between 20 degrees and 40 degrees C.

Inbreeding studies in Brasilian schoolchildren

Abstract: We present results of comparisons between consanguineous and control couples and their children in Southern Brasil. Multiple regression, t-test and χ2 analyses were applied to the data. The following variables were investigated; Parents: structure of first cousin marriages, latitude and longitude of birthplaces, cohabitation time, rurality, marriage age, occupation, number of liveborn children, and frequency of twinning. Schoolchildren: clinical data as classified into 24 discontinuous traits, each one subdivided into two categories (number and severity), and seven continuous traits (weight, height, pulse rate, respiratory rate, systolic pressure, diastolic pressure, and temperature); nutrition indices and biotype; family names; intelligence tests and school performances; birth order, age, hair color, hair type, eye color, and skin color; twinning in the sibship, and infant mortality among sibs of the propositi. Our study showed a) nonrandomness of consanguineous marriages as detected on structural, racial, geographical, and temporal levels; b) a heavy mutational load of about 1.5 lethons acting on infant mortality; c) no inbreeding effect on morbidity in general (with a possible exception of “ear morbidity”, including hearing deficit); d) a modest inbreeding depression on height (a decrease of 2 cm with an increase of 10% of inbreeding); e) a suggestion of inbreeding depression on “intelligence”.

A review of basic ecological processes interacting with production and standing-stock of phytoplankton in lakes and reservoirs in Brazil

Abstract: The author discusses the interactions of the main forcing functions in shallow lakes and reservoirs in Brazil with the functioning of the phytoplankton community from the point of view of primary production and standing-stock. Forcing functions were water level fluctuation, destratification and mixing, wind action and precipitation. One of the major factors controlling variations in productivity and nutrient availability, diurnal variations of environmental factors, is also discussed. Its role in microstratification and replenishment of nutrients to the euphotic zone in shallow lakes is stressed. Major processes in reservoirs are related to residence time, ‘hydraulic stratification’, sediment-water interaction, and cultural eutrophication. Perspectives for future limnological research by a process-orientated approach are given.

Quadratic vector fields with finitely many periodic orbits

Abstract: We prove that vector fields outside an algebraic hypersurface in the space of coefficients of quadratic vector fields in the plane have a finite number of periodic orbits.

Magnetic field influence on the spin-Peierls instability in the quasi-one-dimensional magnetostrictive XY model: Thermodynamical properties

Abstract: We study in detail, within the adiabatic approximation for the structural degrees of freedom and on exact grounds for the magnetic ones, the $d=1$ magnetostrictive spin-\textonehalf{} $\mathrm{XY}$ model in the presence of an external magnetic field along the $z$ axis. We calculate the specific heat, magnetization, isothermal susceptibility, and the structural order parameter and spectrum (including the sound velocity). The system presents, in temperature-field space, three structurally different phases: the uniform ($U$), the dimerized ($D$), and the modulated ($M$) phases (the latter can be either commensurate or incommensurate with the other two). The critical frontiers $U\ensuremath{-}D$ and $U\ensuremath{-}M$ are of the second-order type while the $D\ensuremath{-}M$ one is of the first-order type; all three join at a Lifshitz point. The $U\ensuremath{-}M$ frontier presents a new type of multicritical point on which the frozen structural wave vector vanishes. The phase diagram is quite anomalous for high values of the elastic constant. Several other effects are predicted. The present theory is expected to be applicable to substances like TTF-BDT [tetrathiafulvalinium bis-cis-(1,2-perfluoromethylethylene-1,2-diselenolato)-metal], ${\mathbf{MEM}(\mathbf{TCNQ})}_{2}$ (N-methyl-N-ethyl-morpholinium ditetracyanoquinodimethanide), and eventually the alkali-metal tetracyanoquinodimethanides (TCNQ).

Esofagopatia chagásica na área endêmica de Bambuí - M.G., Brasil

Abstract: Five hundred sixty six unselected chronic chagasic patients from an endemic area (Bambui, Minas Gerais, Brasil) Were Studied clinical and radiologically. The oesophageal transit time method used was the roentgenphotography with 70mm film, with a left incidence profite or righ-anterior oblique aspect. A 8.33% oesophagic dysperistalsis prevalence was verified in these patients. This was specially common after the third decade of life and no difference related to sex was observed. Seventy-two percent of oesophagic dysfunction were ofdegree I, 18% of degree II and 10% of degree III, based on the classification adapted by Rezende. Only one case of dysperistalsis (degree I) was observed among 80 sero-negative patients. The global prevalence of oesophagopathy was 18.3% in 115 patients in whom the acute phase of Chagas'disease was detected up to 27 years before. The proportion of alterations was directly related to the disease evolution time. A significant difference was verified between the above prevalence and the prevalence found in patients without a detectable acute phase. his suggests that the high percentage of oesophagopathy in patients with detectable acute phase was due to a more intense denervation occurring in those cases. A concomitant chagasic chronic cardiopathy was verified in 50% of the cases disptaying oesophagus dysperistalsis, in accord with other Authors. The simplicity of the method used for detecting oesophagus dysfunction and its low operational cost are evident, demonstrating it to be suitable for the social reality present in Chagas'disease endemic areas.

Beginning to read and write; an exploratory study of young children's understanding of metalinguistic terms and graphic conventions

Abstract: Interest in the acquisition of written language has followed several lines of investigation. A number of studies have extended Vygotsky’s (1962, 1978) thesis that writing has its roots in gesture, drawing and symbolic play (Luria 1978, Graves 1983, Gundlach 1982, Dyson 1982, de G6es & Martlew 1983). Some children appear to acquire initial skills with few apparent problems. Spontaneous experiments with writing have been observed before any apparent instruction has been given (Bissex 1980) and a few children have shown an ability to produce written communications before they can read (Chomsky 1979). Writing, however, is a complex representational system. It changes the focus from language used instrumentally (Hakes 1980) to language-asobject (Cazden 1976). Visible language can be manipulated, words broken down into smaller elements, or letters built up into syllables and words. Relating speech to written language, as in the identification of phonemes within words and syllables, requires a certain level of cognitive maturity (Read 1983) and can be a major stumbling block for most children (Liberman et al. 1977). Furthermore, Reid (1966) and Downing (1979) have shown that children do not have clear notions about the activity of reading or fully comprehend the basic terminology used in the course of instruction. Terms such as letter, sound, word, space, etc. are used by adults to facilitate children’s understanding of written language. These are metalinguistic terms in that they require the child to think or talk about language. It is this aspect of development which we are focusing on in this study as we explore young children’s emerging metalinguistic awareness of basic terminology and their understanding of conventions such as spacing and punctuation. We can focus on the term ’word’ to illustrate children’s developing metalinguistic awareness. Papandropoulou & Sinclair (1974) studied word comprehension in young children and observed interesting developmental trends. They found that children from four to five years did not distinguish conceptually between ’word’ and the object or action referred to, thus showing little or no ability to reflect on language. From five to seven years, children regarded words as ’names’, but not till they were over seven did

Chromosomal-polymorphism in forpus-xanthopterygius (psittaciformes, aves)

Abstract: SUMMARYKaryotypic analyses of 41 specimens of Forpus xanlhopterygius (Psittaciformes: Aves) reveal a diploid number of 86 and three different karyotypes were observed. A chromosomal polymorphism is present which involves two pairs of chromosomes. It is suggested that the observed polymorphism resulted from a translocation involving pairs 1 and 5. The significance of this intrapopulation variation is discussed.

A two-level model for hydride precipitation in binary alloys

Abstract: Two-energy-level models or trapping models have been derived and used by a number of workers to describe the behaviour of hydrogen in solid solutions. These models are extended to include hydride formation and therefore to calculate the terminal solubility of hydrogen (TSH). It is assumed that if an attractive (repulsive) interaction occurs between hydrogen and B in an alloy of B in A, the opposite interaction will occur between hydrogen and A in a dilute alloy of A in B. For strong interactions the TSH is increased in both cases. The A and B atoms are assumed to be immobile and therefore the formation of pure A or B hydrides is impossible. The calculated values of the TSH are in agreement with experimental results measured by Westlake and Miller for Nb-Ta alloys.

Competitive interactions between species of freshwater snails: I. Laboratory: Ia. General methodology

Abstract: For the development of laboratory experiments on the competitive interacitons between freshwater snail populations, special snail rooms were set up in the main building of the Research Center "Aggeu Magalhaes". In the current paper, the first of a series on this subject, the general methodology of the laboratory work is described in detail. Using indoor cement channels in which a uniform seminatural environment was created, interactions of freshwater snail populations can be studied with minimal interference of the usual variables. Controlled indoor environmental techniques, as described in the current paper, may also be utilized in different types of experiments in malacology, and represent a substantial technical advance in malacological work.

Responses of the Phytoplankton Community of a Tropical Reservoir (São Paulo, Brazil) to the Enrichment with Nitrate, Phosphate and EDTA

Abstract: The effects of artificial enrichment with nitrate, phosphate and EDTA on the phytoplankton community were studied in the Lobo Reservoir (Sao Paulo, Brazil). After 14 days of in situ incubation, the amounts of suspended matter and chlorophyll a, the numbers of cells and the carotene/chlorophyll ratio were determined. The addition of nitrate and phosphate to water samples produced significant effects on the chlorophyll a and cell counts, while EDTA acted only on the cell production. Both nitrate and phosphate, when analysed individually, caused a decrease in the value of the carotene/chlorophyll ratio. A synergistic effect of the addition of EDTA and N on the suspended matter was observed.

Race, height, and blood pressure in northeastern Brazil

Abstract: In this admixed population with no significant confounding of race and environment, there is an increase of blood pressure with Negro ancestry. There appears to be a direct effect of race on blood pressure in addition to an indirect effect through height.

Absence of long range order above two-dimensions

Abstract: On montre qu'un systeme statistique a d dimensions d'une seule variable U(1), exp(iφ) dont l'hamiltonien est invariant sous la transformation φ(x i ,...,x d )→φ(xi,...,x d )+λ(x 3 ,...,x d ), avec λ une fonction arbitraire

GALVANOSTATIC FORMATION AND REDUCTION OF TIN/TIN OXIDES IN Na2SO4 SOLUTIONS

Abstract: The galvanostatic formation and reduction of tin/tin oxides in oxygenated Na2SO4 solutions with variation of the anodic formation and/or cathodic reduction currents were studied. Two reduction transition times take place, showing the existence of Sn(IV) and Sn(II) in the film. Through these results the composition of the film is analysed.

Estudo experimental de Zygodontomys lasiurus (Rodentia-cricetidae) com cepas de Trypanosoma cruzi

Abstract: Studies on the experimental infection of Zygodontomys lasiurus (Rodentia-Cricetidae) are presented in the current paper. Three strains of T. cruzi were used in the experiments: two, Y and Berenice, were originated from human infection, while the third one was obtained from natural infection in a wild bug Triatoma costalimai. The evolution of the parasitemia was studied and the prepatent and patent periods determined. The tissular tropism and aggressiveness of the strains of T. cruzi were verified through histopathological studies. Results have shown that the parasitemia was always kept at low levels for all the strains. The prepatent period in the infected rodents varied from: 3 to 6 days in the Y strain; 2 to 6 days in the Berenice strain; 6 to 8 in the costalimai strain. The patent period showed the following duration patterns: 14 to 16 days in the Y strain; 26 to 29 in the Berenice strain and 6 to 8 days in the costalimai strain. Tissue damage was predominantly muscular, and the pathological reactions varied from slight to severe.